Robust Lateral Motion Control Of Distributed-drive Electric Vehicle With Network-induced Delays

Compared with traditional electric vehicles(EVs)with centralized powertrains,distributed-drive electric vehicles utilize four in-wheel motors in a coordinated manner for vehicle propulsion.This provides distributed-drive electric vehicles with high efficiency and better space utilization and control flexibility,thanks to the elimination of mechanical transmission systems and the capitalization of high-efficiency working zone of in-wheel motors.With the rapid development of the current automobile industry towards electrification,intellectualization and connectivity,the number of vehicle electronic control systems will see a dramatic increase,together with skyrocketing volume of information exchanged.Due to the deficiency of current in-vehicle bus technology,the existence of network-induced delays in in-vehicle network systems may compromise system stability of controllers.Under the support of the National Key R&D Program of China 'Research on the Key Technologies for the Industrialization of Distributed-drive Electric Vehicles',and taking the distributed drive electric vehicles as the research object,this paper focuses on the robust control of the vehicle lateral motion with network-induced delays.Based on robust control and allocation theories for overactuated systems,system modeling,state estimation,control algorithm design,simulation analysis and experimental verification are systematically conducted.The main research contents and results are as follows:(1)Accurate state estimation for the speed,yaw rate and slip angle of the vehicle is of critical importance for vehicle stability control.An adaptive Cubature Kalman Filter(ACKF)is proposed based on an established 7 degree-of-freedom(DOF)vehicle model.The statistical information of noises is no longer needed,which makes it more robust to the process noise in practical vehicular operation.Theoretical analysis and simulation results verify the effectiveness of the proposed scheme.(2)The influence of network-induced delays and sampling period on the network control system is analyzed.A vehicle lateral dynamics model with time-induced delays is established,which provides the foundation for control synthesis.(3)The stability control method for the distributed-drive electric vehicles with network-induced delays is studied.For the traditional optimal control,it is difficult to accurately solve the two-point boundary value problems with both time-delay and time-advance terms.The sequence approximation method is adopted to convert the original two-point boundary value problems into solving a series of linear two-point boundary value problems without time-delays and time-advance terms.Based on the Lyapunov stability theory,a global robust sliding mode controller is proposed in order to enhance the robustness to the impacts of time-delays,unmatched model dynamics,and external disturbances.(4)The optimal torque distribution algorithm is studied considering the CAN-bus communication failure.The objective function and constraints are formulated,and a torque distribution equation with adjustable weighting coefficients is accordingly established.Then,a torque optimization distribution algorithm based on the quadratic programming is designed,in which a fault-tolerant distribution mechanism with a reconfiguration function is proposed to ensure the vehicle safety.(5)A hardware-in-the-loop simulation platform for the control system of the distributed-drive electric vehicles is established.The platform consists of the rapid control prototype Open ECU,a real-time vehicle simulation system based on the Car Maker software and LABCAR platform,and CAN bus monitoring module based on CANape.The validity and real-time performance of the proposed state estimation and hierarchical control scheme are verified.The robustness to the network-induced delays and the fault-tolerance ability to the communication failure are also validated.